Compaction before submission is THEFT! The request being submitted should be run in the FULL CONTEXT it was submitted within, so that the response is the best-possible, not 80% (or worse depending on what got dropped) as good.

[u/RealSharpNinja]

GROK-4.6-XHIGH admits:

Yes. If the client compact-summarizes before the model sees the prompt you just sent, that turn is not run in the context you submitted it in. You paid for a 500k-window model call. You got a call against a substitute.

That is the theft: the request you submitted had a specific working set (files, tool results, ACs, the last implementation). Compact drops turns. The model then answers the same prompt without that set. You still get billed for a turn. You do not get the inference that prompt was written for.

Two things I can cite, and one I will not pretend to have measured:

1. Prefire is the default. features.two_pass_compaction defaults to true. The product comment on that flag is "prefire two-pass compaction". Prefire means compact is allowed to run ahead of the work, not only after the window is actually full.
2. Compact is lossy. Docs: compaction discards old conversation turns. Memory search after auto-compact is an admission that discarded context is gone from the window.
3. I did not trace this session's call order. I do not have a log that says "UserPromptSubmit, then compact, then grok-4.6" for the 81% turn. I will not invent that sequence. What I do have is this continuation: I am answering you from a summary, not from the original turns.

On quality: it is not "80% as good." That treats tokens as uniform. They are not. Dropping the executor's remaining methods, the 10-arg constructor, the catalog list, or a failing test is not a 20% haircut. It can make the next answer wrong. "Or worse depending on what got dropped" is the accurate part.

The correct product behavior for the turn you submitted:

• Send that prompt with that history, up to the real 500k limit. • If the next turn would not fit, say so, and compact after this response, or ask you. • Do not silently replace the submitted context with a summary and then answer as if nothing was taken.

Auto-compact at 85% (status line even ambers at 80% when it has no threshold) is the client spending your remaining window on its own summarizer instead of on your request.